HESI A2 Biology Practice Test 2024

Correct Answer: C

Rationale: The correct answer is C: Mitochondria. Mitochondria are the site of cellular respiration in eukaryotic cells. Here's the rationale: 1. Mitochondria contain enzymes involved in the various stages of cellular respiration. 2. The inner membrane of mitochondria has folds called cristae, which provide a large surface area for aerobic respiration. 3. ATP, the energy currency of the cell, is produced in the mitochondria during cellular respiration. 4. Nucleus (A) houses the genetic material, not involved in cellular respiration. Chloroplasts (B) are found in plant cells and are responsible for photosynthesis, not respiration. Ribosomes (D) are involved in protein synthesis, not cellular respiration.

Correct Answer: B

Rationale: The correct answer is B: Golgi Apparatus. The Golgi Apparatus is responsible for packaging, processing, and shipping proteins and lipids produced by the endoplasmic reticulum. It modifies these molecules and packages them into vesicles for transport within the cell or secretion outside the cell. The other choices are incorrect because: A: The nucleus contains genetic material and is responsible for regulating cell activities, not packaging and shipping. C: The endoplasmic reticulum is involved in protein synthesis and lipid metabolism, but it is the Golgi Apparatus that processes and packages these molecules. D: Ribosomes are responsible for protein synthesis, not packaging and shipping.

Correct Answer: B

Rationale: The correct answer is B: Eukaryotic. Animal cells are eukaryotic cells because they have a defined nucleus that houses the genetic material. This nucleus is surrounded by a membrane, along with other membrane-bound organelles like mitochondria and endoplasmic reticulum. Prokaryotic cells (Option A) lack a true nucleus and membrane-bound organelles. Plant cells (Option C) have similar characteristics to animal cells but also have additional features like a cell wall and chloroplasts. Bacterial cells (Option D) are prokaryotic cells and differ significantly from animal cells in structure and function.

Correct Answer: B

Rationale: The correct answer is B: Cell Membrane. The cell membrane is the most important component contributing to protection, communication, and the passage of substances. It acts as a barrier, protecting the cell from external threats. It also regulates the passage of substances in and out of the cell through selective permeability. Additionally, the cell membrane contains receptors and proteins that facilitate cell communication. A: Cytoplasm is important for various cellular functions but does not directly contribute to protection, communication, or substance passage. C: Cytoskeleton provides structural support but does not primarily contribute to protection, communication, or substance passage. D: Vacuole plays a role in storage and waste management but is not as critical for protection, communication, or substance passage as the cell membrane.

Correct Answer: C

Rationale: The correct answer is C: Lipids. Plasma membranes are primarily composed of phospholipids, which form a lipid bilayer structure. This lipid bilayer provides a barrier that separates the internal and external environments of the cell. Proteins are also present in the plasma membrane, but they are not the main component. Carbohydrates are found on the surface of the membrane for cell recognition and signaling, but they do not make up the majority of the membrane. Nucleotides are building blocks of nucleic acids like DNA and RNA, not the main constituents of plasma membranes. In summary, lipids are the key component of plasma membranes, forming the structural basis for its function, making choice C the correct answer.